Beate Kunzel, born a German Protestant, quit her secretarial job in Berlin at age 21, moved to Paris to study French, and met Serge Klarsfeld, whom she married in 1963. Serge, a French Jew, had suffered under the Nazis—he, his mother, and his sister having hidden from the Gestapo in Nice in 1943 as his father was arrested, eventually to disappear in the death camp of Auschwitz. Serge in the 1950s studied history at the Sorbonne, received a licence in law from the University of Paris, and was studying at the Institute of Political Studies of Paris when he met Beate.

Serge had worked in an Israeli kibbutz in 1953 and had written a thesis on the “Cooperative Economy in Israel” (1959). In 1966 he visited Auschwitz and in 1967 served as a volunteer in the Six-Day War in Israel.

Beate Klarsfeld in 1967 wrote a series of articles in the leftist newspaper Combat attacking German Chancellor Kurt Kiesinger for his role as a Nazi propagandist during World War II. In 1968 she attended a rally at which he was speaking, charged to the podium, and slapped Kiesinger on the face. She was arrested, tried, and sentenced but was released on probation. In the years to come she and her husband publicized the pasts of other Nazis and wartime collaborators, forcing some resignations from high posts. They also began pressing for prosecution of former Nazi criminals—among whose ranks they included Kurt Lischka, Herbert Hagen, Ernst Heinrichsohn, Jean Leguay, Werner Best, Gustav Richter, Theodor Ganzemüller, Alois Brunner, and, most notably, Klaus Barbie. In the course of their campaigns and demonstrations, Beate was arrested repeatedly and briefly jailed. They also received a number of death threats, and their car was blown up.

Concurrently, Beate Klarsfeld tried to campaign in such Arab capitals as Rabat, Damascus, and Beirut, as well as elsewhere, accusing Arabs of “barbarities” and urging them to let Israel “live in peace.” Almost every summer the Klarsfelds spent a month at various kibbutzim in Israel.

The Klarsfelds’ work was funded by the nonprofit Beate Klarsfeld Foundation.